1. Field of the Invention
The present invention relates to a small watercraft, and more particularly to the layout of engine components within the watercraft and an associated seat design.
2. Description of Related Art
Personal watercraft have become very popular in recent years. This type of watercraft is quite sporting in nature and carries a rider and possibly one, two or three passengers. A relatively small hull of the personal watercraft commonly defines a riders"" area above an engine compartment. An internal combustion engine frequently powers a jet propulsion unit which propels the watercraft. The engine lies within the engine compartment in front of a tunnel formed on the underside of the watercraft hull. The jet propulsion unit is located within the tunnel and is driven by a drive shaft. The drive shaft usually extends between the engine and the jet propulsion device, through a wall of the hull tunnel.
Despite their popularity, many areas have begun imposing restrictions on personal watercraft due in part to the high decibel operating noise of such crafts. Prior personal watercraft have attempted to lessen exhaust and engine noise by a variety of ways. Some personal watercraft exhaust into the tunnel, as taught by, e.g., U.S. Pat. No. 4,811,560, as well as include one or more expansion chambers (e.g., U.S. Pat. No. 5,234,364) in the exhaust system in order to reduce exhaust noise. Some prior watercraft have also lined the engine compartment with a sound insolating material. While such approaches have lessened the exhaust and operating noise associated with the personal watercraft, a need exists for additional noise reduction.
The present watercraft involves several approaches to reduce the operating noise of the watercraft. One approach involves improved sound insulation about the engine compartment, and includes a seat design that facilitates such improvement. Another approach involves silencing the sound that is emitted from the engine compartment through the air ducts of the watercraft. And a further approach involves insulating a portion of the exhaust system. These approaches, as well as others described below, can be used together or alone within a watercraft in order to lessen operating noises of the watercraft.
One aspect of the present invention thus involves a watercraft comprising a hull having a lower hull portion and an upper deck portion. An internal combustion engine is located within the hull and has an output shaft. A propulsion device is carried by the hull and is driven by the engine output shaft to propel the watercraft. The deck portion includes a central elongated pedestal having first and second sections. The firs section is removable attached to the second section and is arranged to form at least a portion of an upper surface of the pedestal. The deck portion also includes a seat with a base. The seat base is removably attached to the pedestal. In a preferred mode, one or more air pockets are defined between the cover and the seat base to provide sound insulation.
The engine compartment also can further silenced by insulation layers about the side walls of a seat pedestal in which at least a portion of the engine is located. In some modes, at least a portion of the exhaust system can also be insulated within such insulation layers.
Another aspect of the present invention involves a watercraft comprising a hull having a lower hull portion and an upper deck portion. An internal combustion engine is located within the hull and has an output shaft. A propulsion device is carried by the hull and is driven by the engine output shaft to propel the watercraft. The hull also includes at least one air duct with first and second ports. The first port is arranged to communicate ambient air from outside the hull, and the second port opens into the hull. A sub-resonator chamber communicates with the air duct at a portion between the first and second ports. The sub-resonator chamber preferably is tuned (i.e., sized and shaped) to reduce noise emitted through the air duct.
In accordance with a further aspect of the present invention, a watercraft is provided comprising a hull having a lower hull portion and an upper deck portion. An engine compartment is formed within the hull and is defined between a fore bulkhead and an aft bulkhead. Each bulkhead includes at least one tube that communicates with the engine compartment. An internal combustion engine is located within the engine compartment and has an output shaft. A propulsion device is carried by the hull and is driven by the engine output shaft to propel the watercraft. With this construction, the bulkheads help silence engine and exhaust noise.
An additional aspect of the present invention involves a watercraft comprising a hull having a lower hull portion and an upper deck portion. An engine compartment is formed within the hull and is defined between a fore bulkhead and an aft bulkhead. A fore air duct opens into the hull forward of the fore bulkhead and an aft air duct opens into the hull rearward of the aft bulkhead. An internal combustion engine is located within the engine compartment and has an output shaft that drives a propulsion device to propel the watercraft. The arrangement of the air ducts relative to the engine and bulkheads further assists in noise reduction.
Further aspects, features, and advantages of the present invention will become apparent from the detailed description of the preferred embodiment which follows.